Virtual networking has attracted significant attention, in recent years. In such implementations, a virtual overlay network is created on top of a network of physical networking devices, also referred to as the underlay network. Formation of a virtual overlay network has a number of advantages over traditional networking: 1.) network addresses can overlap between multiple tenants of the virtual network, 2.) ease of deploying new services as part of the virtual network (e.g., using service function chaining, etc.), and 3.) support for virtual machine (VM) mobility, which can be important in cloud computing environments, among other benefits.
While overlay networks afford quite a bit of flexibility in terms of making configuration changes, the same does not hold true for the physical underlay network. Notably, the creation of a physical underlay network requires calculating configurations, maintaining Internet Protocol (IP) addresses, and booting up each device, all of which can become very complex as the size of the network increases. In addition, once a physical underlay network has been established, adding new physical networking devices to the underlay network can be disruptive to existing traffic in the network.